Vowel length

Arabic is generally regarded as having 28 consonants, 3 long vowels (/a:/,/i:/,/u:/), and 3 short vowels (/a/,/i/,/u/). The opposition between the three long vowels is present in all modern Arabic dialects. In Cairene, the distinction in the short vowels between /i/ and /u/ has been greatly reduced, although it still exists. Some analyses suggest that this reduction has led to the development of an enriched long vowel system, with /e:/ and /o:/ added to the inventory. We chose to limit our voweling to long and short /a/, /i/, and /u/. We found it quite difficult to achieve inter-coder agreement even with this vowel set, and the presence of an /e/ or /o/ vowel was not something that our speakers were able to identify with a great deal of consistency. This may be due to influence from MSA, where formal methods for indicating voweling exist only for /a/, /i/, and /u/. Although empirical evidence does exist of productive minimal pairs involving /e/ and /u/ for some speakers, it did not appear that lack of this opposition affected perception of synthesized Arabic.